A solid state drive (SSD) is a data storage device that uses integrated circuit assemblies as memory to store data persistently. SSDs have no moving mechanical components and this distinguishes SSDs from traditional electromechanical magnetic disks, such as, hard disk drives (HDDs) or floppy disks, which contain spinning disks and movable read/write heads. Compared to electromechanical disks, SSDs are typically more resistant to physical shock, run silently, have lower access time, and less latency.
Many type of SSDs use NAND-based flash memory which retains data without power and is a type of non-volatile storage technology. An important goal of NAND flash development has been to reduce the cost per bit and increase maximum chip capacity so that flash memory may compete with magnetic storage devices like hard disks.
In a single-level cell (SLC) NAND, each cell may exist in one of two states, and store one bit of information per cell. A multi-level cell (MLC) NAND is a solid-state flash memory that uses multiple levels per cell to allow more bits to be stored using the same number of transistors. Some MLC NANDs have four possible states per cell, so they may store two bits of information per cell. TLC NAND (triple level cell NAND) is a type of multi-level solid-state NAND that stores three bits of information per cell of flash media. In certain situations, it may be desirable to manufacture higher storage capacity SSDs with TLC NANDs, in comparison to NAND flash memory that stores one or two bits of information per cell.